I had been having trouble with my speedometer sticking, and
was on the phone with GM as well as talking with the dealer.
I was told by all parties that the problem didn't exist until
it could be verified by someone other than myself.

It had stuck a total of three times, and on the fourth time, I was able
to bring it to the dealership, grab a service guy by the collar, and
simply point to the speedo which was stuck at 60mph.

Finally, they acknowledged the problem and agreed to fix it.

I scheduled this service as well as a PDIM software update, the HVAC
reprogram, and investigation into an air conditioning rattle.
All but the rattle was taken care of on a Saturday (reasonable time
considering all that was to be fixed, dropped off at 9am and picked up
at 3pm)

Though I am happy that they fixed my speedo problem, I'll be forever
weary of dealing with GM and intermittent (yet serious) problems
like a speedometer sticking.

As far as the rattle goes, I didn't give them a 100% complete description
of the problem, and they tried to identify the rattle by putting the fan
on 100%, when it is most prevalent at 50%. Oh well, I'll live with it until
I can bring it in and bring a service engineer for a quick spin.

Thanks to camaropete and others who have tried to help the process
along.